New York Codes, Rules and Regulations
Title 12 - DEPARTMENT OF LABOR
Chapter I - Industrial Board Of Appeals
Subchapter A - The Industrial Code
Part 4 - Low Pressure Boilers
Subpart 4-5 - Specific Requirements For Low Pressure Heating System Boilers
Section 4-5.2 - Safety valves for low pressure steam boilers

(a) Capacity. A low pressure steam boiler shall include a safety valve or valves of a capacity such that with the heat generating equipment operating at maximum, the steam pressure shall not rise more than five psi gage above the maximum allowable working pressure with all valves open. If the minimum valve capacity in pounds per hour is calculated it shall be determined by dividing by 1,000 the maximum Btu output at the boiler nozzle obtainable from the heat generating equipment, or by multiplying the square feet of heating surface by the values given in the following table:

Minimum pounds of steam per hour per square foot of surface

[Note: The following TABLE/FORM is too wide to be displayed on one screen. You must print it for a meaningful review of its contents. The table has been divided into multiple pieces with each piece containing information to help you assemble a printout of the table. The information for each piece includes: (1) a three line message preceding the tabular data showing by line # and character # the position of the upper left-hand corner of the piece and the position of the piece within the entire table; and (2) a numeric scale following the tabular data displaying the character positions.] ******************************************************************************* ******** This is piece 1. -- It begins at character 1 of table line 1. ******** ******************************************************************************* Boiled heating surface Hand-fired Stoker-fired Oil, gas, or Hand-fired pulverized-fuel-fired Fire-tube 5 7 8 8 boilers Water-tube 6 8 10 8 boilers 1...+...10....+...20....+...30....+...40....+...50....+...60....+...70....+. ******************************************************************************* ******* This is piece 2. -- It begins at character 77 of table line 1. ******** ******************************************************************************* Waterwall surface Stoker-fired Oil, gas, or pulverized-fuel-fired 10 14 12 16 77......+...90....+....0....+...10....

Note: When a boiler is fired only by a gas having a heat value not in excess of 200 Btu per cubic foot, the minimum safety valve relieving capacity may be based on the values given for hand-fired boilers above.

The minimum capacity of the valve or valves shall be governed by the capacity marking on the boiler.

(b) Increased capacity. When operating conditions are changed or additional boiler heating surfaces installed, the valve capacity shall be checked and increased if necessary to meet the new conditions. Necessary additional valves may be installed on the outlet piping, providing there is no intervening valve nor any other branching pipes between the additional valves and the boiler.

(c) Accumulation test. If the total capacity of safety valves is not otherwise ascertained they shall be subjected to an accumulation test.

(d) Type. Required safety valves shall be of the spring-pop type, adjusted and sealed to discharge at a pressure not to exceed 15 psi gage. The seats and disks shall be of suitable material to resist corrosion.

(e) Size. No safety valve for a low pressure steam heating boiler shall be smaller than 3/4 inch except in case the boiler and radiating surfaces are a self-contained unit. No safety valve shall be larger than 41/2inches. The inlet opening shall have an inside diameter equal to or greater than the seat diameter.

(f) Lifting device. Each safety valve for a low pressure steam heating boiler shall have a substantial device which will positively lift the disk from its seat at least 1/16 inch when there is no pressure on the boiler.